Sebastian Coe has questioned the nomination of former drugs cheat Justin Gatlin as one of the IAAF's athletes of the year and said he is convinced by research that steroid users can benefit from usage long after they are declared 'clean'.

New findings from the University of Oslo states athletes who take anabolic steroids can retain the advantage of muscle development even decades later.

Gatlin, from the United States, has run the three fastest times this year in the 100 metres, and the fastest times in the 100 metres and 200 metres ever by a man in his 30s.

IAAF vice-president Seb Coe has questioned Justin Gatlin's nomination for the IAAF Athlete of the year

The 32-year-old 2004 Olympic 100m champion Gatlin tested positive in 2006 for excess testosterone and was banned for four years until 2010.

Gatlin's nomination last weekend as one of the IAAF's male athletes saw another nominee, Germany's Olympic discus champion Robert Harting, asking for his own name to be removed.

Lord Coe, an IAAF vice-president said he also had 'big problems' with the nomination.

Speaking at the Securing Sport conference in London he said: 'The only thing I would say is that he is entitled to be competing. I'm not particularly comfortable about it. I think you'd be pretty surprised if I did sit here and was sanguine about that.

'I personally have big problems with that.

Justin Gatlin (left) powers ahead during the IAAF Diamond League Athletics meeting at Lausanne in July

'I have long since believed that, particularly anabolic steroids, but performance-enhancing, muscle-developing drugs, have a long-term effect.

'I don't wish to be dismissive about the Oslo research but I think anybody in the last 20 years that I've known in that world, particularly in sports physiology and biochemistry would tell you that's certainly the case.

'The effect is certainly not transient and we've seen that in the performance of athletes for some time.'

Coe is also chairman of the British Olympic Association but he accepted there was no going back to the days of its lifetime ban for drugs cheats.

Gatlin (right) attempts to chase down Usain Bolt as the American claimed bronze at London 2012

TOP 100m TIMES IN 2014

Athlete

Time

Place

1. Justin Gatlin

9.77secs

Bruxelles (September 5)

2. Justin Gatlin

9.8secs

Lausanne (July 3)

3. Justin Gatlin

9.82secs

Port of Spain (June 21)

4. Richard Thompson

9.82secs

Linz (July 14)

5. Justin Gatlin

9.83secs

Rieti (September 17)

6. Justin Gatlin

9.86secs

Ostrava (June 17)

7. Justin Gatlin

9.87secs

Beijing (May 21)

'I recognise legally and for all sorts of reasons that that particular train has left the station,' he said.

'A life ban, we know from all sorts of challenges, can't be upheld.

'We pushed very hard within the IAAF to get the WADA ban from two years back up to four years.

'I do think sanctions do have to take into consideration the extended effect that anabolic steroids, performance-enhancing drugs, can have on a career even when the athlete is 'clean'.'

Coe added that he will stand for the presidency of the IAAF next year - current incumbent Lamine Diack has said he will step down.

Coe said: 'I've always been clear, if I'm given the opportunity to shape the future of my sport, I will certainly take it.

'If there is a presidential election, I will want to stand for that.'

Professor of physiology at the University of Oslo Kristen Gunderson and his team studied the effect of steroids on mice and believes that the same mechanism is at work in human muscles and that other performance-enhancing drugs would have similar long-term effects.

Gatlin in 2006, the year he was was banned for a maximum of eight years by the US Anti-Doping Agency

Gunderson told BBC Sport: 'I would be very surprised if there were any major differences between humans and mice in this context.

'The fundamental biology of muscle growth is similar in humans and in mice, and in principle any drug that builds muscle mass could trigger this mechanism.

'I think it is likely that effects could be lifelong or at least lasting decades in humans. Our data indicates the exclusion time of two years is far too short. Even four years is too short.'

Thirty-two-year-old American Gatlin served a four-year ban after appeal to arbitration and - after his return to the sport in 2010 - he ran the fastest 100 metres in the world in this year as he clocked 9.77 seconds to claim a dominant victory at the Memorial van Damme in Brussels last month.

Dai Greene (centre) says Gatlin's phenomenal times this year suggest the steroids he took still have an effect

But British 400 metres hurdles champion Dai Greene said: 'He's over the hill as far as sprinting is concerned - he should never be running these times for the 100m and 200m.

'But he's still doing it, and you have to look at his past, and ask how it is still affecting him now, because the average person wouldn't be able to do that.

'Those are incredible performances. Not many people have run that fast separately, ever. To do it on a damp Friday night? I couldn't believe those times.

'It shows one of two things: either he's still taking performance-enhancing drugs to get the best out of him at his advanced age, or the ones he did take are still doing a fantastic job.

'Because there is no way he can still be running that well at this late point in his career.

Gatlin celebrates winning the men's 100m sprint in Rieti, Italy in September to continue his superb year

'After having years on the sidelines, being unable to train or compete, it doesn't really add up. 9.77 is an incredibly fast time. You only have to look at his performances. I don't believe in them.'

The new data casts a further shadow over formerly-banned athletes such as Gatlin, his compatriot Tyson Gay and Britain's Dwain Chambers.

In his defence, Gatlin's agent Renaldo Nehemiah said: 'Justin would have run these times, and faster, had his over-zealous (former) coach Trevor Graham not tried to get him there sooner than he would've naturally gotten there.

'So, what Justin is doing right now, I'm not surprised by that.

'His body is rested for four years, so he wasn't racing. And he was the talent that I always knew he was.'